Generally, a handler device is used to receive devices, such as integrated circuit (IC) devices, present such devices to a test apparatus, and remove the devices after testing. In such an environment, the IC devices may be referred to as devices under test or “DUTs.” Tested devices may be sorted based on the results of the testing. Based on the results of a test, the devices may also be calibrated by burning fuses inside them.
Testing may be performed under a range of conditions. In some such cases, the DUTs may be placed within an environmental chamber in which temperature, humidity, and/or other conditions may be controlled.
Certain applications present particular challenges. For example, many modern accelerometers are micro electro-mechanical systems (MEMS) devices which are capable of detecting acceleration up to very high ranges, well in excess of fifty times the acceleration of gravity (i.e., greater than 50 g). In order to fully test these devices, it is necessary to subject the MEMS devices to such accelerations in a controlled manner, while the MEMS devices are operating, and to review the measurements provided by the MEMS devices.
U.S. Pat. No. 7,683,608 describes a handler for acceleration testing of electronic components. An acceleration device is disclosed in which a DUT is held on a nest that is attached to the free end of a tappet. The other end of the tappet is connected to a coil motor that moves the tappet back and forth in an axial direction at a certain frequency. One drawback of such system is that a large force is required to accelerate the DUT, nest, and tappet at sufficiently high levels. Accordingly, the motor must be large enough to generate such a force, requiring a large amount of energy. Further, generation of the large force results in high levels of stress on the motor, possibly hastening wear and reducing the life of the motor. Such a system may also be incapable of functioning properly when placed in an environmental chamber. These constraints impose practical limitations on the level of acceleration that can be achieved and the overall durability of the system.
Another method of testing accelerometers utilizes controlled impact. With this method, a device at a set velocity undergoes an impact with a hard surface or spring. This method can produce high acceleration magnitudes, but may give an erratic acceleration profile, may not be sufficiently repeatable, and may not produce a profile with a sufficiently long period to fully characterize a device.
Yet another method involves mounting devices onto a rotating drum and having the acceleration obtained from the centrifugal forces on the devices. This method still requires a large torque and becomes cumbersome if testing needs to be performed at different levels and in both the positive and negative direction.
It would be advantageous to provide an acceleration device for a handler system capable of accelerating a device to high levels in a controlled, energy-efficient, repeatable manner.